<template>
  <div class="q-pa-md">
    <q-table
      ref="tableRef"
      title="Treats"
      :rows="rows"
      :columns="columns"
      row-key="name"
      :selected-rows-label="getSelectedString"
      selection="multiple"
      :selected="selected"
      @selection="onSelection"
    />

    <div class="q-mt-md">
      Selected: {{ JSON.stringify(selected) }}
    </div>
  </div>
</template>

<script>
import { useQuasar } from 'quasar'
import { ref } from 'vue'

const columns = [
  {
    name: 'desc',
    required: true,
    label: 'Dessert (100g serving)',
    align: 'left',
    field: row => row.name,
    format: val => `${val}`,
    sortable: true
  },
  { name: 'calories', align: 'center', label: 'Calories', field: 'calories', sortable: true },
  { name: 'fat', label: 'Fat (g)', field: 'fat', sortable: true },
  { name: 'carbs', label: 'Carbs (g)', field: 'carbs' },
  { name: 'protein', label: 'Protein (g)', field: 'protein' },
  { name: 'sodium', label: 'Sodium (mg)', field: 'sodium' },
  { name: 'calcium', label: 'Calcium (%)', field: 'calcium', sortable: true, sort: (a, b) => parseInt(a, 10) - parseInt(b, 10) },
  { name: 'iron', label: 'Iron (%)', field: 'iron', sortable: true, sort: (a, b) => parseInt(a, 10) - parseInt(b, 10) }
]

const rows = [
  {
    name: 'Frozen Yogurt',
    calories: 159,
    fat: 6.0,
    carbs: 24,
    protein: 4.0,
    sodium: 87,
    calcium: '14%',
    iron: '1%'
  },
  {
    name: 'Ice cream sandwich',
    calories: 237,
    fat: 9.0,
    carbs: 37,
    protein: 4.3,
    sodium: 129,
    calcium: '8%',
    iron: '1%'
  },
  {
    name: 'Eclair',
    calories: 262,
    fat: 16.0,
    carbs: 23,
    protein: 6.0,
    sodium: 337,
    calcium: '6%',
    iron: '7%'
  },
  {
    name: 'Cupcake',
    calories: 305,
    fat: 3.7,
    carbs: 67,
    protein: 4.3,
    sodium: 413,
    calcium: '3%',
    iron: '8%'
  },
  {
    name: 'Gingerbread',
    calories: 356,
    fat: 16.0,
    carbs: 49,
    protein: 3.9,
    sodium: 327,
    calcium: '7%',
    iron: '16%'
  },
  {
    name: 'Jelly bean',
    calories: 375,
    fat: 0.0,
    carbs: 94,
    protein: 0.0,
    sodium: 50,
    calcium: '0%',
    iron: '0%'
  },
  {
    name: 'Lollipop',
    calories: 392,
    fat: 0.2,
    carbs: 98,
    protein: 0,
    sodium: 38,
    calcium: '0%',
    iron: '2%'
  },
  {
    name: 'Honeycomb',
    calories: 408,
    fat: 3.2,
    carbs: 87,
    protein: 6.5,
    sodium: 562,
    calcium: '0%',
    iron: '45%'
  },
  {
    name: 'Donut',
    calories: 452,
    fat: 25.0,
    carbs: 51,
    protein: 4.9,
    sodium: 326,
    calcium: '2%',
    iron: '22%'
  },
  {
    name: 'KitKat',
    calories: 518,
    fat: 26.0,
    carbs: 65,
    protein: 7,
    sodium: 54,
    calcium: '12%',
    iron: '6%'
  }
]

export default {
  setup () {
    const $q = useQuasar()

    const selected = ref([])
    const lastIndex = ref(null)
    const tableRef = ref(null)

    return {
      selected,
      lastIndex,
      tableRef,

      columns,
      rows,

      getSelectedString () {
        return selected.value.length === 0 ? '' : `${selected.value.length} record${selected.value.length > 1 ? 's' : ''} selected of ${rows.length}`
      },

      onSelection ({ rows, added, evt }) {
        if (rows.length === 0 || tableRef.value === void 0) {
          return
        }

        const row = rows[ 0 ]
        const filteredSortedRows = tableRef.value.filteredSortedRows
        const rowIndex = filteredSortedRows.indexOf(row)
        const localLastIndex = lastIndex.value

        lastIndex.value = rowIndex
        document.getSelection().removeAllRanges()

        if ($q.platform.is.mobile === true) {
          evt = { ctrlKey: true }
        }
        else if (evt !== Object(evt) || (evt.shiftKey !== true && evt.ctrlKey !== true)) {
          selected.value = added === true ? rows : []
          return
        }

        const operateSelection = added === true
          ? selRow => {
            const selectedIndex = selected.value.indexOf(selRow)
            if (selectedIndex === -1) {
              selected.value = selected.value.concat(selRow)
            }
          }
          : selRow => {
            const selectedIndex = selected.value.indexOf(selRow)
            if (selectedIndex > -1) {
              selected.value = selected.value.slice(0, selectedIndex).concat(selected.value.slice(selectedIndex + 1))
            }
          }

        if (localLastIndex === null || evt.shiftKey !== true) {
          operateSelection(row)
          return
        }

        const from = localLastIndex < rowIndex ? localLastIndex : rowIndex
        const to = localLastIndex < rowIndex ? rowIndex : localLastIndex
        for (let i = from; i <= to; i += 1) {
          operateSelection(filteredSortedRows[ i ])
        }
      }
    }
  }
}
</script>
